QSqlError("", "Unable to fetch row", "No query")

create_sql = "create table member (id int primary key, name varchar(30),address varchar(30))";    insert_sql = "insert into member values(?,?,?)";    select_sql = "select * from member";
    db = QSqlDatabase::addDatabase("QSQLITE");    db.setDatabaseName("xin.db");    if(db.open())    {      qDebug()<<"database open!";
      sql_query = QSqlQuery::QSqlQuery(db);   /////////////      sql_query.prepare(create_sql);
      if(sql_query.exec())      {          qDebug()<<"table create success!";      }      else      {          qDebug()<<sql_query.lastError();      }

    }
db和sql_query声明的是全局变量，只要第2次运行就会报QSqlError("", "Unable to fetch row", "No query") 把xin.db删了就不会报错，请问这该怎么破？

robinsonsir	2017-09-18 09:31
QSqlQuery sql_query(db); 这里 sql_query = QSqlQuery::QSqlQuery(db); 这不是静态函数啊

jing105630	2017-09-19 16:37
robinsonsir:QSqlQuery sql_query(db); 这里 sql_query = QSqlQuery::QSqlQuery(db); 这不是静态函数啊 (2017-09-18 09:31) 那该怎么写呢，有相关例子可以参考吗？

robinsonsir	2017-09-19 19:29
jing105630:那该怎么写呢，有相关例子可以参考吗？ (2017-09-19 16:37) QSqlQuery sql_query(db); sql_query.prepare(create_sql);

jing105630	2017-09-20 09:11
robinsonsir:QSqlQuery sql_query(db); sql_query.prepare(create_sql); (2017-09-19 19:29) 这个我放在头文件里，放函数内每个操作都要定义

robinsonsir	2017-09-20 09:23
jing105630:这个我放在头文件里，放函数内每个操作都要定义 (2017-09-20 09:11) QSqlQuery tmpQuery(db); sql_query = tmpQuery; sql_query.prepare(create_sql);

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